(a) Field of the Invention:
The present invention relates to a method and apparatus for optical recording and reproduction, and more particularly to a method and apparatus for optical recording and reproduction in which the light spot is prevented from staying on a same track on an optical disk for a time longer than a predetermined one, thereby preventing the optical disk from being deteriorated while maintaining the projected power of a light spot at a high level.
(b) Description of the Related Art:
In the conventional optical recording/reproduction apparatus, after a recording or reproduction is made onto or from a track on an optical disk, the light spot is kept in a position on a track to or from which the recording or reproduction is finally made. It should be noted here that the maximum read power of light spot with which the light spot may be continuously projected without deteriorating the surface of an optical disk depends upon the type of the disk. Therefore, an optical disk of which the maximum read power is low must be used with an optical recording/reproduction apparatus of which the read power of light spot is low. Assume now that an optical disk of low maximum read power is used in an optical recording/reproduction apparatus of which the read power of light spot is high. Since the light spot stays on a same track, the pit pattern, including sector marks, ID parts, data parts, etc. provided on the track are deteriorated, and finally a hole is made in the surface of the optical disk with the result that no data recording/reproduction will be possible.
Therefore, in case optical disks of different types are used in the conventional optical recording/reproduction apparatus, it is necessary to set low the read power of the light spot of the apparatus according as low as the maximum read power of to one of the optical disks of having the lowest maximum read power is the lowest.
In the optical recording/reproduction apparatus of which the read power is set low as in the above, however, the read signal is so weak that the tracking servo system to position the light spot on a track and the auto-focus servo system to focus the light spot are unstable with the result that the signal-to-noise ratio of reproduced data is low.